X光分幅相机在黑腔等离子体填充特性研究中的应用

Characterization of plasma filling in hohlraum using X-ray framing camera

在神光Ⅱ装置上2.4 ns长脉冲三倍频激光(激光能量8×300 J)与腔靶耦合实验研究中,X光分幅相机通过激光注入孔观测获得了3种腔尺寸腔内Au等离子体径向运动时空分辨图像。用MATLAB对图像进行了定量处理,结合时间分辨辐射温度测量结果分析表明:在腔内不充气、无低Z衬垫情况下,标准腔(φ800μm×1350μm)在激光脉冲作用到约1.5 ns时出现明显的Au等离子体堵腔效应;当腔尺寸放大到1.25倍(φ1000μm×1800μm)和1.5倍(φ1200μm×2100μm)时,腔内等离子体基本不堵腔。给出了3种腔尺寸不同时期腔内Au等离子体径向聚心速度,分析表明:大腔的聚心速度比小腔的慢,后期比初期慢。

A microchannel plate gated X-ray framing camera（XFC） was used to take pictures of Au plasma radial conver gence in hohlraums on Shenguang-Ⅱ laser facility. According to XFC image manipulation by MATLAB and measurement of radia tion temperature, hohlraum closure of Au plasma generally will not occur in hohlraums with sizes of φ1 000 μm× 1 800 μm and φ1 200μm×2 100 μm,on condition that there is no gas and low-Z filling in hohlraum, by laser beams with 351 nm wavelength, 2.4 ns pulse duration and 8 × 300 J energy on Shenguang-Ⅱ laser facility. While obvious hohlraum closure of Au plasma would occur in the standard hohlraum（φ800μm×1 350μm） with the laser applied for about 1.5 ns. Additionally, XFC image manipulation unveiled Au plasma radial convergence speed in the three hohlraums, which shows that the bigger the hohraum size and the longer the laser applying time, the lower the speed.